This invention relates to electronics in general, and more particularly, to tuning controls for digital equipment having selectable frequencies of operation.
The advent of digital techniques on radio communications has been significant in recent years, most notably in the increased reliability and precision capable of being attained utilizing the new technology.
A digital radio system will normally be operated in an incremental frequency select mode of operation with the frequency increments matching the required conventions of the spectrum of use. The frequencies are typically selected by utilizing a knob having a plurality of selectable detent positions wherein each position provides a specified digital input to a digital processor resulting in singular frequency output matching the detent position of the switch.
The normal switch input implementation utilizes two frequency select knobs, wherein a first coarse adjustment knob is utilized for rapidly changing the frequency at relatively coarse increments and a second fine increment knob for tuning in between the coarse increments of the first knob. This requires the use of two switches at the very least, and in alternative implementations, a numeric input pad is used requiring at least ten switches for inputting each of the ten digits as desired.
A variety of methods for tuning have been described in the U.S. Pat. No. 3,843,873 issued to Robert E. Beville, Oct. 22, 1974, entitled "Counter Having Selective Direction and Variable Rate Control", U.S Pat. No. 4,309,598, issued Jan. 5, 1982 to James M. Davis, Jr., entitled "Variable Rate Data Entry Apparatus and Method", and the U.S. Pat. No. 4,036,431, issued July 19, 1977 to Lars F. Gidlof, entitled "Method and Apparatus for Use in Setting a Counter". Those patents provide useful background and are hereby incorporated by reference thereto the Davis patent referenced above describes an alternative hardware/software embodiment which facilitates ready application of the instantly disclosed software in its own alternative hardware embodiment. Specific reference is made to Davis FIGS. 1, 3, 4a and 4b and the associated discussion in columns 2-9 for a hardware embodiment and to FIGS. 8, 9 and their associated discussion in columns 9-17 for an alternative software embodiment.